Instant Karma: Donald Trump bashes Biden for his age — then forgets name of his own doctor (video)

It's nice when karma is instant, as it was over the weekend when Donald Trump tried to bash President Biden's cognitive health — only to forget the name of his own former White House doctor.

"He doesn't even know what the word 'inflation' means. I think he should take a cognitive test like I did," the convicted felon said in Detroit, still crowing about the rudimentary memory test he "aced" during his presidency that, according to his own boast, asked him to identify a whale.

"Doc Ronny. Doc Ronny Johnson. Does anyone know Ronny Johnson, Congressman from Texas?" Trump then asked, pointing a finger at his Turning Point audience. "He was the White House doctor." But nope, nobody — including his doctor, who was sitting in the auditorium at his event — remembered Ronny Johnson. (See video below, posted by Acyn.)

"There's nothing like mocking your opponent's mental acuity and messing up the name of your doctor who actually administered your own cognitive test who is sitting in the audience," Morning Joe host Mika Brzezinski later quipped. "The name of Trump's former White House physician-turned-U.S. Congressman is Ronny Jackson, not Johnson."

Previously: Donald Trump glitches out — says Jeb Bush was president who got us into Iraq War (video)